Acid Blue 9 (Uncertified FD&C Blue No. 1 Or D&C Blue No. 4)

What is Acid Blue 9 (Uncertified FD&C Blue No. 1 Or D&C Blue No. 4)?

Acid Blue 9 is a synthetic triarylmethane dye, chemically known as the disodium salt of a complex fluorescein derivative with sulfonate groups for water solubility. Produced via organic synthesis involving condensation reactions, it yields a vivid blue pigment stable in aqueous environments. Commonly incorporated into rinse-off products like shampoos, bath gels, soaps, and toothpastes, as well as leave-on items such as eyeliners and hair colorants. In formulations, it dissolves evenly in the water phase, binding lightly to substrates to deliver intense, long-lasting coloration. This enables precise shade matching, corrects natural variations in base materials, and enhances product vibrancy without impacting viscosity or cleansing efficacy significantly.

Comedogenic Rating 0/5 Low risk of clogging pores
EWG Safety Rating 10 View on EWG →

Roles in Formulation

This ingredient serves the following purposes in cosmetic formulations:

Colorant
Provides or corrects color using dyes or pigments, helping achieve a consistent shade and visual appearance across batches and throughout wear.

Benefits

Provides intense blue pigmentation for eye-catching product visuals.

Ensures color uniformity and stability across manufacturing batches.

Integrates seamlessly into water-based formulas without compromising texture.

Who It's For

A quick guide for who this ingredient may suit (and who should be cautious).

Who May Benefit Who Should Avoid
Users of blue-tinted bath and hair care items for aesthetic appeal.
Individuals with dye sensitivities or contact dermatitis history.
Beauty enthusiasts selecting vibrantly colored makeup products.
Those preferring natural or impurity-free ingredients.
Formulators needing dependable dyes for rinse-off cosmetics.
People with very reactive skin prone to allergic responses.

Safety Notes

  • Uncertified batches lack purity certification, prompting high hazard scores in databases.
  • Certified equivalents meet regulatory standards, but uncertified risk contaminants like heavy metals.

Frequently Asked Questions about Acid Blue 9 (Uncertified FD&C Blue No. 1 Or D&C Blue No. 4)

What role does Acid Blue 9 play in cosmetics?

It functions as a water-soluble colorant, adding blue shades to shampoos, soaps, and makeup.

Why the safety concerns with Acid Blue 9?

Uncertified versions may harbor impurities absent in certified, batch-tested dyes.

Is Acid Blue 9 irritating to skin?

Evidence points to low irritation potential in typical cosmetic uses.